Apparatus for testing brakes



June 22, 1937.

R. W. ALLEN APPARATUS FOR TESTING BRAKES Filed Sept. 25, 1953 7 Sheets-Sheet l INVENTOR PAW/0N0 n4 ALLEN ATTO RN 5Y5 June 22, 1937. R. w. ALLEN 2,084,547

APPARATUS FOR TESTING BRAKES Filed Sept. 25, 1933 7 Sheets-Sheet 2 INVENTOR RA YHDND W ALLEN ATTORNEYS June 22, 1937. R. w. ALLEN 2,084,547

APPARATUS FOR TESTING BRAKES Filed Sept. 25, 1953 7 Sheets-Sheet 3 INVENTOR 7FA Y/v0/v0 W ALLf/V 7 v BY June ZZ, 1937. R w, ALLEN 2,084,547

APPARATUS FOR TESTING BRAKES Filed Sept. 25, 1953 7 Sheets-Sheet 4 h INVENTOR RA Y/fO/VD W ALLEN ATTORNEYS June 22, 1937. R. w. ALLEN APPARATUS FOR TESTING BRAKES Filed Sept. 25, 1933 7 Sheets-Sheet 5 INVENTOR RA Y/YO/VD W ALLEN ATTORN EYS June 22, 1937. R. w. ALLEN 2,084,547

APPARATUS FOR TESTING BRAKES Filed Sept. 25, 1933 7 Sheets-Sheet 6 El I22 RA YNOND W A LL EN L 59 i J L J INVENTOR ATTORN EYS June 22, 1937. R. w. ALLEN 2,084,547

APPARATUS FOR TESTING BRAKES Filed Sept. 25, 1933 7 Sheets-Sheet 7 INVENTOR RA V/YO/VD H4 A 1. 1. EN

ATTORNEY Y brakes.

Patented June 22 1937 UNITED STATES PATENT OFFICE APPARATUS FOR, TESTING BRAKES Application September 25, 1933, Serial No. 690,816

8 Claims.

* tain when the brakes are in service on motor vehicles.

The chief objects of the invention are to provide'accuracy of results in the testing of brakes; and to provide improved apparatus for testing More specifically, the invention aims to provide brake testing apparatus that is easily adjustable as to its application of torque to the brake being tested, whereby conditions in vehicles A, of different weights are simulated; and to provide automatic features in the apparatus whereby the brake is brought into action as soon as a determinate speed is obtained, and released as soon as one member is brought to rest to avoid back-lash of another member. Other objects wil be manifest.

Of the accompanying drawings;

Figure 1 is a plan View of one embodiment of the improved brake testing apparatus;

Figure 2 is a side elevation thereof, a table hav- 2'5- ing recording instruments thereon being omitted for clearness of illustration;

Figure 3 is a section on the line 33 of Figure 4;

Figure 4 is an end elevation, on a larger scale, of the apparatus as viewed from the left of Fig ure 1;

Figure 5 is a section on the line 5-5 of Figure 1, on a larger scale;

Figure 6 is a detail side elevation of one end portion of another embodiment of the invention;

Figure 7 is a section on the line l'! of Figure 6;

Figure 8 is a. side elevation of still another embodiment of the invention;

Figure 9 is an end elevation thereof;

I Figure 10 is afragmentary elevation, on a larger scale, of some of the mechanism shown in Figure 9; and

Figure 11 is a wiring diagram of certain electrically operated elements of the apparatus.

Referring to the drawings, the apparatus shown in Figures 1 to 5 thereof comprises an elongate base member ID upon one end portion of which is mounted a motor II that drives, through a coupling [2, a transmission device I3 similar to those used in motor vehicles, said transmission being provided with the usual gear shift lever l4, and being supported by a bracket l5 mounted upon base I0. A guard I6 is mounted over a portion of the coupling l2. The'transmission I3 is connected by a coupling ii to the drive shaft of a reduction gear device 18 of which i9 is the driven shaft thereof, said device 58 being analogous to the rear axle assembly of a motor vehicle without the differential gearing.

At one end the shaft I9 is formed with a flange 2: to which is secured the hub 22 of a flywheel, the latter including a normally fixed inertia plate 23 that is secured to said hub, and a plurality of inertia plates 24, 24 of lighter weight mounted upon the hub and removably secured to the fixed plate 23 by bolts 25, 25. Mounted upon the front of hub 22 is a mounting plate 26, and mounted upon the latter, concentric with shaft I9, is a brake drum 21. The arrangement issuch that inertia plates 24 are easily added to or removed from the flywheel so that the inertia and torque conditions in motor vehicles of different Weights are easily simulated.

The end portion of the base l0 remote from the motor I I is formed on its top face with a dovetail slideway 29 upon which is mounted a slide 38, the latter being movable toward and away from the flywheel by means of the usual screw 3| provided with an operating handwheel 32. 30 comprises a bracket 33, the upper portion of which is formed as a bearing for a torque shaft 34 that is in axial alignment with the shaft [9 of the reduction gear device H3. The end of torque shaft 34 that is nearest the flywheel has keyed thereon the hub 35 of a braking structure that comprises a supporting disc 36, brake shoes 31, 31, (Figure 5) and respective brake linings 38 on the brake shoes 31. The brake structure is of the internal expanding type, the brake shoes 31 being expanded mechanically by the usual cam (not shown) that is mounted upon a cam-shaft 39, Figure 5, that projects through the supporting disc 36. In the operative position of the apparatus, the braking structure described is disposed within the brake drum 21.

Mounted upon the projecting end portion of the cam-shaft 39 is a peripherally grooved quadrant 4|, in the groove of which is mounted a short flexible cable 42 that has one of its ends secured to the quadrant and has its other end secured to the outer end of the piston rod 43 of a single-acting fluid pressure operated cylinder 44. A fluid inlet and outlet pipe 45 communicates with the chamber of the cylinder 44 through the upper head thereof, and a bleeder pipe 46 communicates with said chamber through the lower head of the cylinder. The cylinder 44 is supported by a pair of tie-rods 41, 41 that extend downwardly from a yoke 48 that is fixedly mounted upon the The slide hub 35 of the braking structure. The arrangement is such that pressure fluid admitted to the fluid pressure cylinder 44 moves the piston rod d3 downwardly and thereby operates the braking mechanism to spread the brake shoes 37 so that the linings 38 thereof bear against the rotating brake drum 21, with the result that rotation of the latter is frictionally resisted and the drum and its driving elements are brought to rest.

The brake shoes are expanded against the tension of the usual springs (not shown), which springs restore the several parts, including the cylinder piston, to inoperative position when the pressure fluid in said cylinder is released. During the braking operation power to the motor II automatically is disconnected by means presently to be described.

During the braking operation, the torque of the brake drum and its driving means is transmitted through the braking mechanism to the torque shaft 34 on which said mechanism is mounted, said torque being measured by a dynamometer associated with said torque shaft. The dynamometer comprises a torque flange that is secured by bolts 5I to a similarly shaped flange 33a concentrically formed on the bearing portion of bracket 33. Keyed to the outer end of torque shaft 34 is a. torque plate 52 that is formed with four, symmetrically disposed, rectangular apertures 53,53. King posts 54,54 are mounted on the torque flange 5B, and project laterally therefrom through the respective apertures 53 and into respective cylinders 55 mounted on the outer face of the torque plate 52 over said apertures. The cylinders 55 are formed with longitudinally disposed slots 56, Figure 3, to receive the respective king posts, and the end portions of the latter, interiorly of the said cylinders, are provided with respective anti-friction rollers 51.

Each cylinder 55 has heads 59 at its respective ends, each of said heads being formed with a pressure chamber 69 into which projects an axially disposed piston iii. The latter is carried by a guide structure 62 thathas a sliding fit within the cylinder 55, both guide structures 55 in said cylinder normally abutting the roller 51 of king post 54. The chambers 69 are filled with fluid such as oil, and respective conductor pipes 63 extend from each chamber 8!! to a common manifold 64 mounted upon the torque plate 52 at the axis thereof. A fluid conductor pipe 65 extends from the manifold 64 to an instrument panel, presently to be described. The arrangement is such that relative movement of the torque plate 52 and torque flange 58 in either direction will cause four of the pistons 6i to move into their chambers SE] and force the fluid therefrom, whereby the pressure of the fluid in the manifold 54 and pipe 65 is increased, said increased pressure being a function of the torque of shaft 34.

As is shown in Figure 1, an instrument table 6'! is positioned beside the apparatus described, and mounted in said table is a recording device 68 for making a graphic record of the operation of the apparatus. Thus the fluid-conducting pipe 55 is connected to a pressure-operated indicator 5!? associated with the recording device for recording torque. A clock IE3 mounted in the table 51 is electrically connected to a time indicator H associated with the recording device for recording time intervals of one-tenth minute each thereon. A pressure-operated recorder 12 is connected by pipe 73 with fluid-pressure pipe 45 for recording the air pressure in the brake-operating mechanism. An electrically-operatedindicator14 is connected by conductor wires 75 with an electrically operated revolution counter E6 on the reduction gear device l8, whereby the speed of the flywheel and the brake drum 2'? is recorded by the recording device 68.

Niounted on the back of the table 67 is an instrument panel 78. Mounted on the latter is an air pressure gauge I9 connected by pipe 8!] to pipe 45 for visibly indicating the pressure of the brake-operated mechanism. An electrically 0perated indicator is mounted on panel I8 and connected by conductor wires 82 to a tachometer 3 associated with reduction gear device I8 for visibly indicating the speed of the motor I I. Also mounted upon the instrument panel is a cut-off switch 85 that has driving connection, through flexible shaft, 85, with a rotating shaft in the transmission device I3, said switch being electrically connected to a multiple-contact relay switch I26, Figure 11, for operating the latter when the speed of motor II attains a determinate maximum. As shown in Figure 11, switch I 26 has connection, through conductor wires I21, with motor H, and is adapted to open said connection to cut off electrical power to the motor when operated by switch 85 as described. The switch l25 also has electrical connection through conductor wire I28 with a solenoid-operated three-way valve 87 in the pipe 45 whereby said valve is opened to admit fluid pressure to the cylinder 44 to operate the brake mechanism concurrently with the cutting of power to the motor.

A zero speed switch 39 is mounted on the base ill and is belt-driven from any suitable motordriven part, such as the coupling I2 as shown,

said switch being closed when the motor is running and automatically opened as soon as the motor stops. The switch 89 is in parallel with cut-01f switch 85 through a shunt or holdingcircuit I29 that includes one pair of contacts of the relay switch I26, whereby the coil in relay switch I26 is maintained in energized condition after the conductors l2? to motor II have been opened, and switch 85 opens due to the slowing down of the motor. As soon as motor II stops, switch 89 opens, thus de-energizing the coil of relay switch I26 and causing the latter to resumeits normal condition shown, with the result that conductor I28 is opened and valve 81 permitted to close. This shuts ofl fluid pressure to the brakeoperating mechanism and exhausts cylinder 44 so that said mechanism returns to inoperative position. The arrangement results in the releasing of the brake as soon as the motor II stops rotating so that back-lash of the dynamometer is not transmitted to the driving mechanism of the apparatus. A clock 93 on panel 18 may be provided for eflecting automatic starting of the motor I l at determinate time intervals, so that after the brake drum 2? and brake lining 38 to be tested are in place in the apparatus, the testing thereof is automatically accomplished and a permanent record of results is made. i

The operation of the apparatus may be briefly summarized as follows. The motor II is automatically started by clock QiLand upon attaining determinate speed its power is cut off by switch 85 which also acts concurrentlyfto operate solenoid valve 8! to admit fluid pressure to cylinder t4, whereby the brake is applied to brake drum 2?. With the application of the brake, the, torque of the flywheel and the shaft H is transmitted to torque shaft 34, said torque being yieldingly resisted by the dynamometer and the magnitude of the torque being recorded by the device 68. 75

As soon as the braking mechanism has brought the driving mechanism to rest, the zero speed switch 89, acting through solenoid valve 81, releases the fluid pressure in cylinder 44 and thus releases the brake so that the back-lash of the dynamometer is not transmitted to the brake and driving mechanism. This completes one cycle of operation which is repeated automatically at timed intervals as the clock again starts the motor.

The feature of mounting the braking mechanism on the slide 30 facilitates the inspection, mounting, and removal of the brake band and brake drum, and also facilitates the mounting and removal of the inertia discs 24 on the flywheel whereby the torque is varied. The apparatus permits the testing of brakes under various conditions such as are met with in service on motor vehicles, and achieves the other advantages set out in the foregoing statement of objects.

The embodiment of the invention shown in Figures 6 and '1 is identical with that previously described except in the dynamometer employed. Said dynamometer comprises a radial torque arm 02 that is mounted upon the end portion of torque shaft 34a and extends downwardly therefrom, the free end of said torque arm being slotted to receive a link 93 to which it is pivotally connected at 94 at the middle thereof. Upon each end of link 93 is pivotally mounted a piston or presser pad 95 that normally engages a flexible diaphragm 96 that constitutes one side of a chamber 91 formed in a bracket 98 that is mounted upon slide 30a. The chambers 91 are filled with fluid such as oil, and respective pipes 99 extend therefrom to a manifold (not shown) that communicates with a recording device such as that shown in the previously described embodiment. The arrangement is such that the torque of the torque shaft 34a moves the arm 92 to compress the fluid in one of the chambers 91, and thereby to record said torque in terms of pressure on the recording device. This type of dynamometer is simpler than that previously described, but is not balanced as is the latter.

The embodiment of the invention shown in Figures 8 to 10 inclusive comprises a base member I00 upon one end of which is mounted a motor Ifli, the other end portion of the base being extended upwardly so as to constitute a housing 509a for reduction gear mechanism (not shown),

the latter being connected to the motor by a coupling I02. A zero speed. switch I03 is shown mounted on the base I00 and belt-driven from the motor shaft. The driven shaft of said reduction gear mechanism projects from the front of the housing IBM and carries a flywheel I 04, also a wheel I05 that is arranged to rotate with said shaft, thesaid wheel carrying a tire I06 and a brake drum I01.

Journaled upon the outer end of said driven shaft is a braking mechanism comprising hub structure I09, and pivotally mounted at H0, H0 thereon are brake shoes I II provided with respective brake linings I I2 to be tested, said brake shoes being disposed adjacent the inner periphery of the brake drum I01. The hub I09 also carries a fluid pressure-operated wheel cylinder II3 that is connected to the free ends of brake shoes III and an inlet and outlet pipe II4 supplies pressure fluid to said cylinder from a source of supply (not shown). The arrangement is such that charging of cylinder II 3 spreads the free ends of brake shoes III so that their brake linings II2 frictionally engage the inner surface of brake drum I01. A tension spring II5 has its respective ends connected to the brake shoes III for withdrawing them from the brake drum when the fluid pressure is released in the cylinder II3.

When the brakes are applied to the rotating brake drum I01 the torque of the latter is transmitted to the brake hub I00, and for measuring said torque said hub is provided with a radial, substantially horizontal torque-arm H1 that has its free end connected by a link I I8 to a reducing arm I i9 that is fulcrumed at its adjacent end upon a fulcrum link I20. The latter is pivotally suspended from a spindle IZI that is carried by a laterally projecting bracket arm I22 formed on an upwardly-extending, forwardly overhanging scale-support I 23 that is mounted upon the housing portion 500a of the base member I00. Suspended from the scale-support H3 is a scale or spring balance I24 to the lower end of which is operatively connected the free end of reducing arm H0. The arrangement is such that the torque applied to hub I09 is transmitted through the leverage described to the scale I24, which has a suitably calibrated dial for visibly indicating the magnitude of said torque. The apparatus may be provided with the other instrumentalities (not shown) necessary for automatic operation, similar to the arrangement shown in the first described embodiment of the invention.

The feature of mounting a wheel and tire on the brake testing apparatus especially adapts it for demonstration purposes since the brake is shown in conjunction with devices with which brakes usually are associated. The wheel and tire also supplement the flywheel in producing torque comparable to that to which the brake is subjected in service.

Modification may be resorted to without departing from the spirit of the invention or the scope of the appended claims, which are not limited wholly to the specific construction shown and described.

What. is claimed is:

1. Apparatus for testing brakes, said apparatus comprising a brake drum, means for rotating the same, braking mechanism associated with the brake drum, yielding means restraining the braking mechanism against rotation, means controlled by the rotative speed of the drumrotating means for applying the braking mechanism to the brake drum and for retracting it therefrom whereby torque transmitted from the brake drum through the braking mechanism deforms said yielding means, and means for measuring the deformation of said yielding means as a function of the magnitude of said torque.

2. In apparatus for testing brakes, the combination of a brake drum, means for rotating the same, braking mechanism associated with said brake drum, means controlled by the speed of the drum rotating means for applying the braking mechanism to the drum, and means for measuring the torque transmitted by the brake drum to the braking mechanism.

3. In apparatus for testing brakes, the combination of a brake drum, means for rotating the same, braking mechanism associated with said brake drum, means for applying the braking mechanism to the drum to stop the rotation thereof, means for measuring the torque transmitted by the brake drum to the braking mechanism, and means operated by the stopping of rotation of the brake drum for automatically releasing the braking mechanism immediately the drum is brought to rest.

4. In apparatus for testing brakes, the combination of a brake drum, means for rotating the same, braking mechanism associated with said brake drum, means controlled by the drum rotating means for applying the braking mechanism to the drum when the latter attains determinate speed, means for measuring the torque transmitted from the brake drum to the braking mechanism, and means for releasing the braking mechanism immediately the drum ceases rotating.

5. In apparatus for testing brakes, the combination of a brake drum, means for driving the .1 same including an electric motor, braking mechanism associated with the brake drum, means controlled by the speed of the drum-driving means for concurrently shutting oif power to the motor and applying the braking mechanism to the brake drum when the rotation of the brake drum attains determinate speed, and means for measuring the magnitude of the torque transmitted from the brake drum to the braking mech anism.

6. In apparatus for testing brakes, the combination of a brake drum, means for driving the same including an electric motor, braking mechanism associated with the brake drum, means for concurrently shutting off power to the motor and w applying the braking mechanism to the brake drum when the rotation of the brake drum attains determinate speed, means for releasing the braking mechanism immediately the drumcomes to rest, and means for measuring the magnitude of the torque transmitted from the brake drum to the braking mechanism.

7. In apparatus for testing brakes, the combination of a brake drum, means for driving the same, brake mechanism associated with the brake drum, means for applying the braking mechanism to the drum, a journaled shaft supporting the braking mechanism, a plurality of symmetrically arranged yielding means carried by the shaft, a plurality of stationary abutments cooperating. with said yielding means for resisting angular movement of the same, and means associated with said yielding means for determining the torque transmitted from the brake drum to the braking mechanism during a braking operation.

8. In apparatus for testing brakes, the combination of a brake drum, means for driving the same, brake mechanism associated with the brake drum, means for applying the braking mechanism to the drum, a journaled shaft supporting the braking mechanism, means for moving said shaft axially to change the position of the braking mechanism with relation to the brake drum, yielding means resisting angular movement of said shaft in either direction, and means associated with said yielding means for determining the torque transmitted from the brake drum to the braking mechanism during a braking operation.

RAYMOND W. ALLEN. 

